Field
Aspects of the present disclosure relate generally to wireless communication systems, and more particularly, to optimizing search length for reselection cell searches.
Background
Wireless communication networks are widely deployed to provide various communication services such as telephony, video, data, messaging, broadcasts, and so on. Such networks, which are usually multiple access networks, support communications for multiple users by sharing the available network resources. One example of such a network is the UMTS Terrestrial Radio Access Network (UTRAN). The UTRAN is the radio access network (RAN) defined as a part of the Universal Mobile Telecommunications System (UMTS), a third generation (3G) mobile phone technology supported by the 3rd Generation Partnership Project (3GPP). The UMTS, which is the successor to Global System for Mobile Communications (GSM) technologies, currently supports various air interface standards, such as Wideband-Code Division Multiple Access (W-CDMA), Time Division-Code Division Multiple Access (TD-CDMA), and Time Division-Synchronous Code Division Multiple Access (TD-SCDMA). The UMTS also supports enhanced 3G data communications protocols, such as High Speed Packet Access (HSPA), which provides higher data transfer speeds and capacity to associated UMTS networks.
As the demand for mobile broadband access continues to increase, research and development continue to advance the UMTS technologies not only to meet the growing demand for mobile broadband access, but to advance and enhance the user experience with mobile communications.
In UMTS networks, mobile devices, such as user equipment (UE), may intermittently search for cells other than the cell currently serving the UE to determine whether one or more candidate cells exist that would provide more reliable or stronger service than the current serving cell. Currently, when in idle mode, when the signal strength of the serving cell is less than a threshold signal strength value, the UE may trigger a full search for these candidate cells, for example. This full search may include a step 1 search, which may include a full search subset, such as, but not limited to, a step 1 search, step 2 search, step 3 search, or any other search type described by specifications disseminated by the Third Generation Partnership Project (3GPP). In an aspect, a full search, or a portion of a full search, such as a step 1, 2, 3, or other search subset of a full search, may have a non-coherent integration length that may be, or may not be, related to the coherent integration length. For purposes of the present disclosure, the term “coherent integration” may refer to a process whereby a received signal is correlated with a known signal sequence, such as a signal sequence stored on memory or otherwise obtained and known by a UE. Further, for purposes of the present disclosure, the term “coherent integration length” may refer to a number of samples over which correlation takes place. Additionally, for purposes of the present disclosure, the term “non-coherent integration” may refer to a process wherein the energies from multiple coherent integrations (e.g. correlations) are added together. Furthermore, for purposes of the present disclosure, the term “non-coherent integration length” may refer to the number of coherent integration energies are added up during a particular non-coherent integration process.
Furthermore, in an aspect, following completion of the step 1 search in a full search, the UE may perform a step 2 and/or a step 3 search, which each extend the total full search time and demand additional power resources. Implementing such a full search whenever a candidate cell search is triggered consumes non-negligible amounts of power and sometimes impacts standby time significantly. Therefore, methods and apparatuses are needed for improving cell reselection candidate searching processes in wireless systems.